/**
 * Given a non-negative integer num, repeatedly add all its digits until the result has only one 
 * digit.For example:
 * Given num = 38, the process is like: 3 + 8 = 11, 1 + 1 = 2. 
 * Since 2 has only one digit, return it.
 */
/**
 * @author I321035
 *
 */
package problem258_Add_Digits;